Jesus Antonio Hernandez Jr., the 18-year-old wanted in connection with the July 4 murder of Osvaldo Tinajero in Antioch surrendered to police early Tuesday.
He is being held without bond on charges of criminal homicide and attempted criminal homicide.
Police say Hernandez, whose street name is "Joker," and other members of a Hispanic gang crashed a rival Hispanic gang's party at 625 Ransom Village Way.
The rival gang members were asked to leave, which they did, but not before heated words were exchanged, police said.
Some members of the rival group returned at approximately 1:15 a.m. on July 4, including 18-year-old Tinajero and a 17-year-old.
Hernandez implicated himself in the case during an interview with South Precinct Detective Corey Wall on Tuesday morning, police said.
Witnesses reported that Hernandez fired a pistol, striking Tinajero and the 17-year-old, according to police.
Tinajero died shortly after arriving at a local hospital. The 17-year-old survived.